Near-Earth Object Telescope at Purple Mountain Observatory captures 2024YR4 on Jan 7, 2025. The small bright spot pointed to by the red arrow is the asteroid. [Photo provided to chinadaily.com.cn]

Those worrying about the 2 percent likelihood of 2024 YR4 — a near-Earth asteroid discovered in December 2024 — colliding with the Earth on Dec 22, 2032, should find solace in reports that China is readying a defense system against near-Earth asteroids.

Wu Yanhua, then deputy head of the China National Space Administration, once exposed that China is developing a defense system against near-Earth asteroids that could collide with the Earth. This month, the State Administration of Science, Technology and Industry for National Defense issued a notice recruiting staff members, including three "asteroid defense" jobs, which is being interpreted as China's preparation for a long-term asteroid defense plan. It plans to launch the Tianwen 2 probe this year, which will return with samples from near-Earth asteroid 2016 HO3. This will test the technologies involved in conducting round trips from asteroids using the anchor-and-attach method.

In 2022, the US National Aeronautics and Space Administration conducted a planetary defense experiment called the Double Asteroid Redirection Test, in which it launched a spacecraft toward asteroid Didymos and its small moon Dimorphos.

After a nine-month journey, the spacecraft released an impactor that collided with the asteroid's small moon at a speed of 6.6 kilometers per second, generating an explosive force equivalent to 3 tons of TNT. The impact altered the orbit of the asteroid's small moon. In October last year, the European Space Agency launched mission Hera to the same heavenly bodies.

When astronomers discovered 2024 YR4 on Dec 27, they realized the asteroid had narrowly encountered Earth two days ago, being just 828,800 km away, a little more than twice the distance between the Earth and the moon.

The 2024 YR4 is the greatest risk mankind has faced from an asteroid in the past 20 years, second only to 99942 Apophis, which, in 2004, had a 2.7 percent chance of colliding with the Earth in 2029. But more recent calculations say the possibility of 99942 Apophis colliding with the Earth in the next 100 years is believed to be zero. Should it collide, however, it is estimated it would have the combined explosive power of all nuclear weapons currently possessed by humanity.

Maybe the likelihood of 2024 YR4 colliding with the Earth will gradually dwindle, but it makes sense to be prepared. For that the major astronautical powers of the world must join hands to shield mankind from disaster to the greatest extent possible.